144 ANNUAL REPORT SMITHSONIAN INSTITUTION, 1919. 
Green- | mper- || GreeD- | per- Green- | mpor. || GreeD- | mor. 
wich!) ome ACHE cate Wee ree vee aie 
ean 
eter. time eter. 
d. h. m, = d. h. m. - d. h. m. : d. h.m. - 
28 22 45 82.4 |] 28 23 30 80.6 |} 29 0 15 82.0 |} 29 1 0} 83.8 
23 0 84, 2 45 82.4 30 82.4 15 | 84.2 
15 82.4 ||} 29 0 0 80. 6 45 83.1 30} 84.2 
15. On June 7, having completed the development, we left Sobral 
for Fortaleza, returning on July 9 for the purpose of securing com- 
parison plates of the eclipse field. 
Before our departure we dismounted the mirrors and driving clocks 
which were brought into the house to avoid the exposure to dust. 
The telescopes and ccelostats were left in situ. Before removing 
the mirrors we marked their position in their cells so that they could 
be replaced in exactly the same position. 
After our return to Sobral the mirrors and clocks were remounted ; 
the photography of the eclipse field was commenced on the morning 
of July 11 (civil). The difficulty of finding the field with the ccelo- 
stats was overcome by making a rough hour circle on the heads of 
the celostats out of millimeter paper. 
The following is the list of exposures made on the field for com- 
parison with the eclipse photographs: 
[The reference numbers follow the civil dates.] 
Astrographic telescope. 4-inch telescope. 
Refer- Green- | Num- Refer- Green- | Num- 
ence Date: wich | ber of | Dura- | Alti- | ence bates wich | ber of Dura- Alti- 
num- mean | expo- | tion. | tude. | num- mean | expo- } tion. | tude. 
ber. time. | sures. ber. time. | sures. 
h.m S$. < h.m 8 3 
My 4) duly 10.) 20° 5 3 a 28. 9 14, | July 13] 20 7 2 25) 32.4 
Ile 20 16 2 5 31. 1 14 20 16 2 20} 34.3 
113 20 21 1 5 32. 2 
14, | July 13] 2013 3 5 33. 7 15; | July 14! (2017 2 20} 35.4 
142 20 17 2 5 34.5 152 20 22 2 20} 36.4 
143 20 19 2 5 34.9 
15, | July 14} 2015 3 5 34.9 17, | July 16] 20 6 3 15| 34.7 
152 20 20 2 5 36. 1 172 20 24 2 15} 38.6 
153 20 23 2 5 36. 6 
li1. | July 16} 20 2 4 3 33. 8 
179 20 15 3 3 36. 6 18 | July 17| 19 57 3 20} 33.6 
173 20 23 2 3 38.3 183 20 24 2 20} 39.2 
1% 20 25 2 5 38. 8 
18, | July 17| 19 50 3 4 32.8 
182 20 1 2 4 34, 4 
183 20 20 3 4 38. 6 
18, 20 25 2 3 39.5 
J 
1 The 4-inch plate, No, 18, was taken through the glass (see sec. 17, infra) to facilitate the measurement 
and is referred to as the scale plate. 
